When comparing Webpack vs Mocha, the Slant community recommends Mocha for most people. In the question“What are the best tools for front-end JavaScript development?”Mocha is ranked 2nd while Webpack is ranked 3rd. The most important reason people chose Mocha is:

Mocha runs independently from the [assertion library](http://visionmedia.github.io/mocha/#assertions), so you can choose which assertion format works best for you.
Mocha most often is run in combination with assertion library [Chai](http://chaijs.com).

Pros

Pro

Rich and flexible plugin infrastructure

Plugins and loaders are easy to write and allow you to control each step of the build, from loading and compiling CoffeeScript, LESS and JADE files to smart post processing and asset manifest building.

Pro

Tap into npm's huge module ecosystem

Using Webpack opens you up to npm, that has over 80k modules of which a great amount work both client-side and server-side. And the list is growing rapidly.

Pro

Supports source maps for easier debugging

Source maps allow for easier debugging, because they allow you to find the problems within the origin files instead of the output file.

Pro

Share the same modules client-side and server-side

Because Webpack allows you to use the same require() function as node.js, you can easily share modules between the client-side and server-side.

Pro

ES6 module support

Webpack supports ES6 modules and their import and export methods without having to compile them to CommonJS require

Pro

Bundles CommonJs and AMD modules (even combined)

Webpack supports AMD and CommonJS module styles. It performs clever static analysis on the AST of your code. It even has an evaluation engine to evaluate simple expressions. This allows you to support most existing libraries.

Pro

Can create a single bundle or multiple chunks loaded on demand, to reduce initial loading time

Webpack allows you to split your codebase into multiple chunks. Chunks are loaded on demand. This reduces the initial loading time.

Pro

Mix ES6 AMD and CommonJS

Webpack supports using all three module types, even in the same file.

Pro

Limit plugin integration issues

Pro

Supports different assertion libraries

Mocha runs independently from the assertion library, so you can choose which assertion format works best for you.

Pro

Write tests with Behavior Driven Development (BDD)

Allows developers to choose their development process. Not only TDD but also BDD.

Pro

Makes Asynchronous testing extremely easy

No need to write tricky statements for Async testing. Mocha gives you a done callback. Place this done parameter in your callback function, that'll let Mocha know that you've written an asynchronous function.

Pro

Runs in Node.js and the browser

Mocha has a browser build as well as a node command line program so you can test in client and server side environments.

Pro

Custom full color test reporters

Mocha has multiple test reporters built in and you can create your own as well. The test reporters have full color and makes it easy to see if your tests fail or not.

Pro

Easy to add support for Generators

Aside from the numerous benefits with generators in your application, You can now also integrate generators into your test suite. By using mocha, all you have to do is enable support for generators.

Cons

Con

Config file may be hard to understand

Due to a somewhat hard to grasp syntax, configuring Webpack may take some time.

Con

Can be intimidating for beginners

While some testing frameworks are complete out of the box, Mocha requires developers to select and set up assertion libraries and mocking utilities. For someone who is just starting to learn how to build tests this can be scary as they will also have to choose which libraries to use and learn them too.